As a method for manufacturing a ceramic honeycomb structure, an extrusion method has heretofore broadly been performed by using a die for forming a honeycomb structure (hereinafter referred to simply as the “die” sometimes) including a die base which is provided with back holes for introducing a forming material (clay) and lattice-like slits or the like for communicating with these back holes. In this die, one surface of the die base is usually provided with the lattice-like slits each having a width corresponding to a partition wall thickness of the honeycomb structure, and the opposite surface (the other surface) thereof is provided with the back holes which communicate with the slits and which have large opening areas. Moreover, the back holes are usually arranged at positions where the lattice-like slits intersect with one another, and the back holes and the slits communicate with each other in the die base. Therefore, a forming material such as a ceramic material introduced from the back holes moves from the back holes having a comparatively large inner diameter to the slits having a small width, and is extruded as a formed body (a formed honeycomb body) of the honeycomb structure from openings of the slits.
As the die base constituting such a die for forming the honeycomb structure, there is used a die base including a plate-like member made of one type of alloy such as a stainless alloy or a hard metal alloy, or there is used a die base which is constituted by laminating and bonding two different types of plate-like members, for example, a plate-like member where the slits are to be formed and a plate-like member where the back holes are to be formed (e.g., Patent Documents 1 and 2).
In a conventional method for manufacturing the die for forming the honeycomb structure, the above-mentioned slits and back holes are formed in such a die base by machine processing.
Patent Document 1: Japanese Patent Application Laid-Open No. 2000-326318
Patent Document 2: Japanese Patent Application Laid-Open No. 2003-285308